Peripheral units are generally known in the related art. The company Siemens AG produces the ET20OU modular peripheral unit, for example. In the conventional design of automation systems, sensors and actuators are connected directly to the central automation unit. In the case of widely branched systems, this leads to complex wiring systems with high wiring costs, and reduced flexibility in the event of changes and additions.
Local peripheral units thus form an efficient interface between the process and the central automation unit. The processing and conversion of the process signals, the interaction with sensors and actuators, is carried out directly on site, that is to say, is also physically assigned to the process or the process element. The connection between the peripheral unit and the central automation unit is, in this case, normally produced via a field bus, and thus via a single connection.
Furthermore, integral peripheral units having a high degree of protection (IP66/IP67) are known, for example, the ET200C peripheral unit marketed by the company Siemens AG, which are primarily suitable for use in a harsh industrial environment.
In contrast, no peripheral units are known in which the necessary electrically conductive connections between the individual modules are produced during expansion without any additional contact means, such as plugs or cables. Furthermore, no modularly expandable peripheral units are yet known in the related art which can be expanded in a modular manner while at the same time affording a high degree of protection.